Update: Experts weigh in on use of tear gas in Dorner case

Catch up:Special Section: Manhunt Tactical deputies' decision to use pyrotechnic tear gas grenades at the conclusion of their confrontation with multiple murder suspect Christopher Jordan Dorner has aroused some suspicion that responders intended to burn their quarry alive, but retired law enforcement sources with command and training experience say available evidence does not support that conclusion.

Dorner died - likely by his own hand - inside a Barton Flats cabin that caught fire after SWAT deputies deployed tear gas canisters that generate heat to to disperse incapacitating chemicals.

The decision to deploy the tear gas grenades was made near the end of a roughly four-hour pursuit and series of gun battles that took place between Dorner and law enforcement last Tuesday in the San Bernardino Mountains.

While attempting to flee the Big Bear Lake condo where he had hid during a several days' manhunt, Dorner fired on pursuing state Fish and Game wardens before barricading himself in the cabin from where he then fatally shot sheriff's detective Jeremiah MacKay and seriously wounded Deputy Alex Collins.

Dorner then exchanged gunfire with other law enforcement officers, and local news stations broadcast the sounds of heavy gunfire over live television.

Had an officer's bullet killed Dorner during the firefight, there would likely be few - if any - questions about whether responders had a legal right to use lethal force. Although autopsy results reported Friday that Dorner died of a possibly self-inflicted gunshot SWAT deputies' decision to use pyrotechnic tear gas canisters that could cause a fire has led to many questioning authorities true motives.

The issue is whether the SWAT deputies deployed pyrotechnic tear gas grenades with the specific intention of setting the cabin ablaze with the potential to burn Dorner alive inside, as opposed to using the tear gas for its traditional purpose of incapacitating a violent suspect.

Recordings of the live broadcast have prompted considerable discussion in online forums that the fire was intentionally set.

Although television stations broadcast live audio from the Barton Flats standoff in which unspecified individuals can be heard exclaiming phrases like "burn the gas" or "Burn this (expletive), retired law enforcement leaders said those words reflect the fact that tear gas grenades are known as "burners" in SWAT parlance, and are not indications that tactical responders planned to set the cabin ablaze.

"This is not the U.S. Army chasing John Wilkes Booth into a barn, and they couldn't get him out so they burn the barn down," said Gregory D. Lee, a retired Drug Enforcement Administration supervisor and FBI Academy instructor.

Sheriff's officials have confirmed the cabin fire ignited after deputies deployed the hot tear gas canisters, but have emphatically denied SWAT members purposefully used the grenades as incendiary devices.

"I can tell you that it was not on purpose. We did not intentionally burn down that cabin to get Mr. Dorner out," Sheriff John McMahon said at a brief news conference on Wednesday.

To some, however, the official story does not match what they heard on television. Audio broadcast live by news stations including CBS 2 and KCAL 9 have segments that have convinced some that deputies planned to light the cabin on fire.

"Burn it down," one voice can be heard shouting on a KCAL 9 video posted to YouTube.

"Get going right now,"replies what sounds like another man on the ground.

On the CBS 2 audio feed, a voice or voices can be heard exclaiming "Shoot the gas ... get the gas ... burn the gas. Burn the gas."

A third item on YouTube, represented as being a recording of scanner traffic from the Tuesday battle, includes audio of a voice saying "We're going to go forward with the plan, with the burn like we talked about."

"Seven burners deployed and we have a fire," a male voice says.

"Copy. Seven burners deployed and we have a fire," a female voice replies.

Friday, McMahon said the shouted words that seemed to indicate deputies' plans to burn the cabin were made by people who were not part of the tactical team immediately outside the cabin and reflected the emotions of men who were dealing with a dangerous situation.

"We're looking into this and will deal with it appropriately," McMahon said.

The videos have attracted several comments from viewers convinced SWAT members intentionally started the fire.

The Sheriff's Department has not responded to a formal request filed under the California Public Records Act for transcripts and recordings for the day's 911 calls and dispatch transmissions.

Public reactions to the broadcast audio illustrate the discrepancy between a SWAT officer's use of the word "burn" and a layperson's understanding, retired police chief Stan Kephart said.

By saying "burn," a tactical officer would be simply referring to the grenade's ability to generate heat.

"He's not saying, `I'm going to burn this house down," Kephart said.

Kephart is the former chief of the Salt River Police Department, which has more than 100 sworn officers and provides police services to the Salt River Pima-Maricopa Indian Community in Arizona.

At least one former law enforcement leader, however, has acknowledged being troubled by last Tuesday's audio broadcasts.

On CNN, anchor Ashleigh Banfield played the KCAL 9 recording and asked former assistant FBI director Tom Fuentes if the intentional use of fire would have been justified.

"Normally I would so `no, it's not justified.' If he was in the process of actively shooting at those officers at that moment, then they would have to return fire. But if there was any chance that he could surrender, they would have to accept his surrender," Fuentes told Banfield."Now in this case, when they don't see him, and they don't know exactly what's going on, and we don't actually know at this moment what whoever is yelling in that microphone is seeing. And I think that's the important thing here, so there could be other factors leading to this, leading to him to shout that. But in a way, rather than just fire bullets at that cabin, if he was firing at them at that moment, for any reason you don't hear it in the recording, you would think you would hear gunshots in the background. So really, I'm at a loss to explain, why if that's an officer yelling those commands and yelling `burn it down,' I really don't understand why that would be the case," Fuentes continued.

Sheriff's officials have reported the recovery from the cabin of at least two weapons equipped with silencers, although it's not clear which guns Dorner used at different points in the engagement.

At the cabin, deputies found a Glock 19 9mm semi-automatic pistol equipped with a suppressor as well as an AR-15 or M4-type rifle equipped with a suppressor, forward grip, tactical light and scope. The Sheriff's Department revealed the weapons' discovery at Friday's news conference where they provided additional details on the firefight and the use of tear gas.

The sheriff's account of Tuesday's events sounds like a war story.

Dorner, while attempting to flee Big Bear Lake after two residents discovered him hidden in a condo, was driving a stolen Nissan Rogue along Highway 38 when he was discovered by state Fish and Game wardens, who gave chase. The stolen vehicle report that began Tuesday's climactic events was made at 12:22 p.m.

Dorner crashed the Rogue into a snowbank and carjacked another motorist. While driving in his second stolen vehicle of the day, he fired upon the pursuing wardens.

Following the afternoon's first exchange of gunfire, Dorner crashed into another snowbank and ran from the highway, toward the cabin where his life would end within hours.

Sheriff's Detective Jeremiah MacKay and Deputy Alex Collins were the first law enforcement officers to arrive at the cabin, although they did not know Dorner was hidden inside when they saw footprints in the snow.

Dorner saw them first, and opened fire. This happened around 1:15 p.m.

"Our officers had not even pulled their guns out," Sgt. Trevis Newport said while describing Dorner's attack at Friday's news conference.

MacKay died of wounds sustained in the ambush and Collins, who was seriously hurt, was expected to undergo multiple surgeries. Both men were airlifted to Loma Linda University Medical Center while the firefight was ongoing.

"Responding officers arrived and actually went through a hail of gunfire to rescue these two injured deputy sheriffs," McMahon said Friday.

As responders converged upon the cabin area, television stations broadcast the sounds of several guns being fired. This takes place shortly after 1:30 p.m.

"The bullets were snapping through the trees as more deputies showed up," said Sheriff's Capt. Gregg Herbert, who leads the department's specialized enforcement division and was at the scene of Tuesday's firefight. "The entire time we were there, he was shooting at us when we moved. We were required to take cover the entire time we weren't returning fire."

Herbert went on to say Friday that pyrotechnic tear gas was not deployed until after deputies used "cold" tear gas and offered Dorner a chance to turn himself in.

"We used an allied agency's armored vehicle and deployed cold gas into the cabin," he said. "There was no response from the suspect. None. No movement. We felt that based upon his behavior, he was laying in wait for us. If we tried to enter the cabin, there would be another gun battle. A very close-quarters gun battle, so an entry on the cabin was not an option for the safety of our officers."

"We then made the decision to deploy (a) pyrotechnic chemical agent, which is much more effective in saturating the structure, and getting good saturation, a lot of gas and hopefully, to force Mr. Dorner to surrender or come out. He did not surrender," he continued.

In his online manifesto, Dorner declared "my own personal casualty means nothing" and threatened "you can not prevail against an enemy combatant who has no fear of death."

Herbert, however, said tactical deputies still gave Dorner a chance to turn himself in before SWAT members deployed gas grenades.

"Before we put that pyrotechnic chemical agent in, we made numerous PA announcements identifying him by name, asking him to surrender, telling him who we were and asking him to come out," Herbert told reporters. "And then the pyrotechnic chemical agent was inserted. As the fire continued to spread, when about a quarter of the cabin was on fire, we heard a distinct, single gunshot come from inside the house, which was a much different sounding shot from the shots when he had been shooting at us, which indicated to me that a different kind of weapon had been fired."

Herbert declined to say how many gas grenades deputies used in their final attempt to subdue Dorner.

A retired deputy said those who confronted Dorner in the mountains acted professionally.

"Everything was done by the book and it was proper procedure," said Todd Widick, a former San Bernardino County Sheriff's deputy who currently runs a tactical firearm training school, Gun Shots Fire Arm Training, in Ontario.

"You use tear gas to get the suspect to exit period," he said during a phone interview. "After you give them verbal commands from the P.A., the next move is to shoot the tear gas."

Given Dorner's violence and stated willingness to die, Kephart and Lee said the suspect himself decided how last week's battle would end.

For Lee that means that while the SWAT team would have been cognizant the gas grenades could have started the fire, the fire risk was worth using a weapon that may have been able to stop Dorner from continuing his fight.

"I don't think it does any good to negotiate. The guy decided he was going to die in a firefight with police," he said.

The sheriff's department has not confirmed how many gas canisters were used, the department did show examples of cold and hot gas delivery systems at Friday's news conference.

All of the gas systems were manufactured by Defense Technology, a part of the Safariland Land group that specializes in less lethal weapons systems for law enforcement.

The gas products on display Friday included the "Ferret," a 37mm round designed to be fired into windows or through weak materials at barricaded suspects. The Ferret is a cold system that delivers tear gas on impact.

The other gas grenades on display Friday were among Defense Technology's pyrotechnic offerings. The "Pocket Tactical Grenade," "Triple-Chaser Grenade" and "Spede-Heat" grenade all employ heat to disperse tear gas. Defense Technology's product specifications for all three grenades warn they "should not be deployed onto rooftops, in crawl spaces or indoors due to its fire-producing capability."

That statement, Kephart said, has more to do with the manufacturer's need for legal cover than a hard rule telling responders to never throw pyrotechnic gas grenades inside a building during a dangerous situation.

"The manufacturer of these devices has a herd of attorneys who tell tell them, `You have a liability issue here if you don't have this product warning,"' Kephart said.

In a telephone interview last week, Yale pharmacologist Sven-Eric Jordt, who has published research on tear gas, said pyrotechnic gas grenades can start a fire, but tear gas itself is not particularly flammable and the canisters are not typically used to start fires.

Jordt said the fire at the cabin was probably an accident. Larry Smith, a former Fontana officer who has also worked as a trainer for the San Bernardino County Sheriff's Academy, said Thursday he found the deputies' use of the gas grenades to be a smart decision.

"I don't think they really wanted to burn it down. A couple officers might have said something," Smith said in reference to the shouts that could be heard during Tuesday's broadcasts.

Dorner, also believed to be responsible for the killings of Riverside police officer Michael Crain and Irvine couple Monica Quan and Keith Lawrence, wrote in his manifesto that he was seeking revenge against law enforcement officers and their families.

The suspect was a Navy veteran who was fired from the Los Angeles Police Department in 2009. He claims to have been wrongly fired for report his training officer's use of force, and Quan's father represented Dorner during the proceedings that ended with his dismissal.

LAPD chief Charlie Beck has announced the department will reinvestigate Dorner's claims.

Kephart said Beck made the right call. Had Dorner allowed SWAT teams to arrest him, there would be less fuel for conspiracy theorists for conclude Dorner was killed to protect a cover-up.

"The point is, there would have been value for the police service and everyone else to take him alive and have a trial," Kephart said.